Hi , i am stuck on my calculus hw.
The question is just expand and simplity,
1,(4i-j) *j answer= -1
2,k*(j*-3k) answer= -3
i don't get on he got this answer thx,.
The question is just expand and simplity,
1,(4i-j) *j answer= -1
2,k*(j*-3k) answer= -3
i don't get on he got this answer thx,.
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Another way to look at these problems would be to put it in a vector coordinate form where a*i + b*j + c*k = . From here we rewrite the two expressions:
(4i-j) * j = <4,-1,0> * <0,1,0>
k * (j-3k) = <0,0,1> * <0,1,-3>
When doing dot product, you get a scalar from the vector product because you multiply i to i, j to j, and k to k. So the first section we get -1 because it is 4*0+(-1)*1+0*0. The second question is 0*0 + 1*0 + 1*-3 which equals -3.
Hopefully this works for you.
(4i-j) * j = <4,-1,0> * <0,1,0>
k * (j-3k) = <0,0,1> * <0,1,-3>
When doing dot product, you get a scalar from the vector product because you multiply i to i, j to j, and k to k. So the first section we get -1 because it is 4*0+(-1)*1+0*0. The second question is 0*0 + 1*0 + 1*-3 which equals -3.
Hopefully this works for you.